1. Field of the Invention
The present invention relates to binding proteins including antibodies and binding fragments thereof that bind to HER-3 and polynucleotides encoding the same. Expression vectors and host cells comprising the same for the production of the binding protein of the invention are also provided. In addition, the invention provides compositions and methods for diagnosing and treating diseases associated with HER-3 mediated signal transduction and/or its ligand heregulin.
2. Background of the Technology
The human epidermal growth factor receptor 3 (HER-3, also known as ErbB3) is a receptor protein tyrosine kinase and belongs to the epidermal growth factor receptor (EGFR) subfamily of receptor protein tyrosine kinases, which also includes HER-1 (also known as EGFR), HER-2, and HER-4 (Plowman et al., Proc. Natl. Acad. Sci. U.S.A. 87 (1990), 4905-4909; Kraus et al., Proc. Natl. Acad. Sci. U.S.A. 86 (1989), 9193-9197; and Kraus et al., Proc. Natl. Acad. Sci. U.S.A. 90 (1993), 2900-2904). Like the prototypical epidermal growth factor receptor, the transmembrane receptor HER-3 consists of an extracellular ligand-binding domain (ECD), a dimerization domain within the ECD, a transmembrane domain, an intracellular protein tyrosine kinase domain (TKD) and a C-terminal phosphorylation domain.
The ligand Heregulin (HRG) binds to the extracellular domain of HER-3 and activates the receptor-mediated signaling pathway by promoting dimerization with other human epidermal growth factor receptor (HER) family members and transphosphorylation of its intracellular domain. Dimer formation between HER family members expands the signaling potential of HER-3 and is a means not only for signal diversification but also signal amplification. For example the HER-2/HER-3 heterodimer induces one of the most important mitogenic signals among HER family members.
HER-3 has been found to be overexpressed in several types of cancer such as breast, gastrointestinal and pancreatic cancers. Interestingly a correlation between the expression of HER-2/HER-3 and the progression from a non-invasive to an invasive stage has been shown (Alimandi et al., Oncogene 10, 1813-1821; deFazio et al., Cancer 87, 487-498; Naidu et al., Br. J. Cancer 78, 1385-1390). Accordingly, agents that interfere with HER-3 mediated signaling are desirable. Murine or chimeric HER-3 antibodies have been reported, such as in U.S. Pat. No. 5,968,511, U.S. Pat. No. 5,480,968 and WO03013602.
A humanized monoclonal antibody against HER-2, Herceptin®, has recently been shown to interfere with HER-2 mediated signaling and is therapeutically effective in humans (Fendly et al., Hybridoma 6, 359-370; Hudziak et al., Mol. Cell. Biol. 9, 1165-1172; Stebbing et al., Cancer Treat Rev. 26, 287-290). Herceptin® has been shown to act through two different mechanisms, i.e. the engagement of the effector cells of the immune system as well as a direct cytotoxic, apoptosis inducing effect.
However, only patients with highly amplified HER-2 respond significantly to Herceptin® therapy, thus limiting the number of patients suitable for therapy. In addition the development of resistance to drugs or a change in the expression or epitope sequence of HER-2 on tumor cells may render even those approachable patients unreactive with the antibody and therefore abrogating its therapeutic benefits. Therefore more drugs for target based therapies approaching further members of the HER family, such as HER-3, are needed.